This report presents the findings of a project sponsored by the API to determine the effects of smooth dents and rock dents on the integrity of liquid petroleum pipelines in order to avoid unnecessary repair or replacement of pipelines affected by dents if they do not constitute a threat to pipeline serviceability. The addendum to the report presents a description of work which was done after the completion of Phase I. Additional work has been done to address issues confronted but not resolved in the first phase of the work, and to address new issues raised by the first-phase work. API 1156-A is not included with your purchase.